Fix source of flakiness in newtests/ide
Fix source of flakiness in newtests/ide

Summary:
This morning Appveyor was sporadically failing the newtests/ide
test, specifically the second test: "Recheck behavior".

While writing the newtests/ide/lazy test, I noticed that tests could be
flaky when something like this happens:

1. Step A does something that causes some ide messages to be sent
2. Step A makes no assertions about ide messages
3. Step B does something causes some ide messages to be sent
4. Step B makes assertions about ide messages

On a fast computer, the test will pass, since the ide messages triggered
by step A fire before step B runs. On a slow computer, the ide messages
triggered by step A might show up during step B.

The fix is to make step A wait for the ide messages to appear.

I made a pass over this test looking for actions (adding code, adding
files, sending ide notifications) that weren't waiting for the triggered
ide messages. I only found this one.

Reviewed By: samwgoldman

Differential Revision: D5863480

fbshipit-source-id: c71c1ca38563df5dd3ee9517fbf29c3768c55c46

JonathanUsername/flow,gabelevi/flow,popham/flow,gabelevi/flow,gabelevi/flow,claudiopro/flow,gabelevi/flow,JonathanUsername/flow,gabelevi/flow,samwgoldman/flow,popham/flow,JonathanUsername/flow,nmote/flow,gabelevi/flow,AgentME/flow,samwgoldman/flow,samwgoldman/flow,jamesgpearce/flow,mroch/flow,claudiopro/flow,claudiopro/flow,ylu1317/flow,MichaelDeBoey/flow,popham/flow,mroch/flow,facebook/flow,ylu1317/flow,JonathanUsername/flow,samwgoldman/flow,popham/flow,mroch/flow,facebook/flow,facebook/flow,samwgoldman/flow,samwgoldman/flow,facebook/flow,claudiopro/flow,jamesgpearce/flow,popham/flow,TiddoLangerak/flow,jamesgpearce/flow,nmote/flow,JonathanUsername/flow,MichaelDeBoey/flow,nmote/flow,TiddoLangerak/flow,MichaelDeBoey/flow,mroch/flow,JonathanUsername/flow,jamesgpearce/flow,nmote/flow,samwgoldman/flow,AgentME/flow,jamesgpearce/flow,jamesgpearce/flow,popham/flow,mroch/flow,AgentME/flow,nmote/flow,ylu1317/flow,facebook/flow,facebook/flow,facebook/flow,gabelevi/flow,ylu1317/flow,nmote/flow,ylu1317/flow,jamesgpearce/flow,TiddoLangerak/flow,TiddoLangerak/flow,popham/flow,mroch/flow,claudiopro/flow,mroch/flow,AgentME/flow,nmote/flow,TiddoLangerak/flow,JonathanUsername/flow,MichaelDeBoey/flow,MichaelDeBoey/flow,AgentME/flow